The Internet of Things demands much of sensors. RF sensors are among the things being developed in the Microelectronics Research Unit.

6G is a great leap also for electroceramics

The Microelectronics Research Unit is bringing high-frequency electroceramics to 5G and 6G research at the University of Oulu. The frequency range that extends to the terahertz level requires nanoelectronics that operate in the millionths of a millimetre. 

Value Chain. This concept encompasses the trump card of the Microelectronics Research Unit in the area of electroceramics research. Professor Heli Jantunen, who brought value chain thinking into the unit, sheds light on the concept:
"We are developing new and better functioning electroceramics for the needs of industry. We are keeping in mind what kind of a product the material will be used for, we design the components, and we think about the best way to manufacture it."
Managing the whole is part of the core knowledge of the working group led by Jantunen. "The world does not have another research unit that would have such an extensive combining ability. I know it because I know all of the other units", she laughs.
The wholes, for their part, are changing. In the near future the Internet of Things, the networking of devices and machines, will bring a massive amount of different types of sensors and transducers into our everyday lives.  This poses new requirements for electroceramics: for example, energy conservation and environmental friendliness will become necessities.
Both have already been included in the goals of the Microelectronics Unit. "We aim to avoid both toxic and critical substances, such as rare metals.  This is required simply by the huge volumes of the factories of our customers", Jantunen says.
Meanwhile, the traditional method of manufacturing electroceramics, sintering in temperatures of over 1,000 degrees Celsius, consumes huge amounts of energy.  For this reason, the unit has become the first in the world to develop compositions from which electroceramics can be manufactured at "ultra-low" temperatures. In addition, they enable the use of complicated ceramic components and the combination of several functions on the same platform.
"These compositions fall into two classes. Those that are manufactured at room temperature are based on soluble ceramics. The solution is pressed tight, so the liquid that is saturated with a ceramic reacts to pressure and crystallizes into a solid object. Meanwhile, those that are sintered at 300 - 500 degrees are composites of ceramics and glass."

Toward energy harvesting and nanoelectronics


In 2017 the Microelectronics Research Unit presented KNBNNO, a revolutionary material that opened a new area of research. The way that it harvests energy is suitable for sensors and intelligent transport, for instance.

There is also another path to saving electricity: collecting, or "harvesting" energy. This works through the piezoelectric effect: a piezoelectric electroceramic converts an electric charge into kinetic energy (for example, the vibration of a mobile telephone) or conversely, reacts to kinetic energy, such as vibration or compression, by producing an electrical charge. 
The harvesting of energy is needed for dealing with the massive amounts of sensors in the Internet of Things. In the Microelectronics Research Unit, it involves uses in the prototype stages, such as industrial measurement techniques, wearable electronics, and applications that measure levels of human activity.
Despite the targets for use again requires a mastering of the whole. "Industrial equipment requires a different kind of energy harvester than what is needed for the measurement of human respiration", explains Jantunen. "There are very many developers of piezoelectric electroceramics, but most merely develop a material, and that's it. We do the whole value chain."
However, there is no other group in the world that would have developed a "multiharvester", an electroceramic composite that collects energy out of light and heat, in addition to movement. Such a material is KNBNNO, which the Microelectronics Research Unit introduced in 2017. KNBNNO opened a completely new area of research (such multiharvesting had not previously been considered possible) and the development work is still in the beginning stages. One of the greatest challenges is to maximise the phenomenon by adjusting the composition.
KNBNNO brings a more versatile and efficient harvesting method alongside piezoelectric materials, and can add to them when the availability of kinetic energy varies, such as in intelligent transport or wearable electronics. A shared goal looms in the future: the replacement of batteries and charging of them.
In the future harvesting is to be combined with the compositions in ultra-low temperatures. "Testing is under way. It would combine two really new things", says Academy Research Fellow Jari Juuti.
The inclusion of nanotechnology is also something new. The reason once again is the Internet of Things. It will be based on 5G and 6G wireless data transfer that takes place at radio frequencies that are much higher than the current ones. The frequency range that extends into the terahertz region brings up nanoelectronics to electroceramics, which operates in millionths of a millimetre, says Heli Jantunen.
"We will probably go into component structures that do not yet exist.   We are a research unit in high-frequency electroceramic materials in 5G and 6G research at the University of Oulu."

The trip to the top began in the 1970s

The operating model of the Microelectronics Research Unit can be summarized followingly: industry says what is needed, the unit produces new information and combines findings of research into innovations. "And at intervals of about five years we will open new areas of research quite deliberately."
Consequently, international research contacts must operate in every direction, and there needs to be demand for the knowledge we have at Oulu if information is also intended to get from others.  An important mean in this is the increase in the number of top-level published articles.
"We publish 40-50 research articles each year. We solely publish in international scientific journals and we strive to get papers into the best of them.  In this field, the impact factor, which describes the significance of an publication, is usually at about 3 at most, and with many of our publications it is now on both sides of 10", Jantunen says. 
The unit has been moving up to the top of the research community since the 1970s. Electroceramic development work, which began with power electronics, moved on to superconductors, printable electronics, and piezoelectric sensors and micromotors.  Piezoelectric energy harvesters appeared on the scene about ten years ago. Industrial financing of the unit has grown, and now has a little over 70 percent share. The unit consists of researchers from many fields, comprising about 50 people, which has been built like a jigsaw puzzle by recruiting the required expertise from China, Japan, Hungary, Nigeria, India, Brazil...
"We have cooperation with every continent except Antarctica", Jantunen explains. 

Main image: The Internet of Things demands much of sensors. RF sensors are among the things being developed in the Microelectronics Research Unit.

Text: Jarno Mällinen

Last updated: 30.5.2018